I've been cursing AVCHD ever since it started showing up in camcorders and still cameras that shoot video. I don't really understand why it exists. Although its file and folder specification claims to be compatible with Blu-ray, it doesn't seem likely that the majority of casual video shooters will choose to archive video content from cameras directly onto Blu-ray discs, and AVCHD's awkward multiple-folder storage structure makes it extremely difficult to work with in video editing workflows. Some cameras save video directly to MP4 files or have the option to do so (everyone video person I know loves this). But on many cameras (e.g. Sony Cybershot TX7) the highest-quality video format is AVCHD-only. Frustrating!
I'm building an underwater 3D rig that will use dual Sony HDR-CX550V camcorders. I really like the CX550V but hate that it is an AVCHD camcorder. Standard AVCHD editing workflow on Mac OS X requires a time-consuming import process via iMovie or Final Cut Pro. During import, video is transcoded into user-specified, computer-friendly codecs and video file wrappers. Most serious shooters I know archive a disk image of the camcorder / camera's storage volume in order to preserve AVCHD's folder structure and then transcode video to some flavor of ProRes 422 (wrapped in Quicktime) during import. The imported video files are then used as master files. But ProRes consumes a huge amount of disk space, and it seems like a waste to use it to store footage from a point & shoot camera like the Sony TX7.
Within the context of AVCHD workflow, I'm not sure why I don't hear more about Divergent Media's [ClipWrap](http://www.clipwrap.com/). The product has a modest webpage that says, "Easily rewrap m2t, mts, and m2ts files into QuickTime movies."
In a nutshell, what ClipWrap does is take the H.264 video content stored in AVCHD files and re-wrap it into workflow-friendly Quicktime (MOV) files. This solution is lossless, preserving the original video file as it was recorded (including time code, if available). Converted files can be opened directly in Quicktime (with Perian installed) or imported into Final Cut Pro and other video editors. ClipWrap can also transcode to other codecs upon conversion, but I don't see myself ever doing that.
Video: ClipWrap converts AVCHD files copied from the Sony CX550V camcorder
ClipWrap is absolutely indispensable for Mac OS X users working with AVCHD cameras. It has completely done away with the most painful part of my AVCHD video workflow, and I wish I had discovered it earlier.
ClipWrap is $49.99. A [free demo](http://www.clipwrap.com/downloadtrial.php) is available, which limits conversions to the first minute of each clip (I bought it 30 seconds after I tried the demo).